fix cold start time increase issue

[kinderyj]

Fixes #15477

Proposed Changes

• For Kubernetes clusters without mesh enabled, it's preferable to probe the pod directly. However, if podsAddressable is set to false, the activator will continuously probe the cluster, leading to significantly longer cold start times. To re-enable pod probing, you must restart the activator pod. This is because the podsAddressable setting resets to its default value of true only during the activator's startup and initialization.

Release Note

Fix cold start time increase issue.